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 Post subject: Re: prop question for westerbeke 40
PostPosted: 24 Jun 2015 07:52 
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Midshipman

Joined: 01 Nov 2014 12:50
Posts: 68
Location: Toledo
Just launched our new aquisition (hull#4, "Skybird" K/CB with Westerbeke 40.
had a 16x12 fixed two blade on it (which we never had the opportunity to run ).
We just put on a 2-blade 17" feathering max-prop. It all runs smooth and nice so far, but on our initial test our tach ( which needs to be verified for accuracy) only shows us getting 2200 rpm WOT. (3000 WOT is optimum).
pitch was set to 20 DEG (11.6 inches).
Prop manual says about 15% change of rpm for each step in pitch change.
next three steps down in pitch are: 10.4, 9.1, and 8
Anyone else use a similar set up on a W-40?

I am going to check the tach for accuracy, then check throttle linkage to make sure it travels fully. Engine is smooth and not smoking, so no performance issues that I can tell. But if the above tests pass, my guess is to lower pitch by two steps to 9.1
does this sound in line for a 17" prop on a W-40?


 
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 Post subject: Re: prop question for westerbeke 40
PostPosted: 24 Jun 2015 13:05 
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Midshipman

Joined: 01 Nov 2014 12:50
Posts: 68
Location: Toledo
Just checked the tach against a photo tach. About 500 rpm difference at WOT.
So now the WOT RPM is At 2650.
I checked the throttle cable and observing the travel at the fuel injection, I see there is a screw adjustment that limits the open throttle speed. Idea
I cannot find any info on this adjustment in the W--40 manual, but it seems I would need to unscrew this adjustment and carefully throttle up JUST until rpm stops increasing. At that point I would note the WOT RPM, then turn the screw back in until it just starts to take a couple R's off at WOT.

Does this seem right? Anyone else deal with these adjustments? Seems I will not get a true reading of prop performance until I make this throttle adjustment.


 
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 Post subject: Re: prop question for westerbeke 40
PostPosted: 28 Jun 2015 08:23 
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Midshipman

Joined: 01 Nov 2014 12:50
Posts: 68
Location: Toledo
Okay my source told me to adjust to 3220 WOT in neutral.
I was able to get 3160 before it appeared the adjustment screw was no longer effective.
Subsequent testing shows us getting 3060 rpm @ WOT in gear, underway.
according to the manual for the propellor, I would be looking at as much as 450 rpm drop by pitching up.
so I think I have it as close as I can get.
will adjust max throttle to just under 3000 rpm and call 2400 rpm the max cruising speed.
Also will see if I can calibrate the tach to read correctly at 2400 rpm.

Next engine project (after we get the mast up) is to replace the leaky exhaust elbow.
Cool


 
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 Post subject: Re: prop question for westerbeke 40
PostPosted: 02 Jul 2015 07:33 
Offline
Midshipman

Joined: 01 Nov 2014 12:50
Posts: 68
Location: Toledo
Just some performance followup notes.
W-40 17" 2- blade feathering max prop.
we are reaching 6.4 knots at 2200 rpm.
6.6 @ 2400 (80% throttle)

Did not check it at WOT, but the proportion of engine work/noise/ fuel consumption appears to increase almost infinitely above 6.5 knots (GPS speed).
I doubt we will reach 7 knots at WOT.


 
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